The Blue band member, 30, was taken into custody in the early hours of April 11 after police officers allegedly found illegal drugs in his car during a search.
He was taken to a police station for questioning and charged with failing to provide a specimen after refusing to take a breath test. Ryan was later hit with an additional charge of criminal damage after he allegedly urinated all over his holding cell.
Ryan told Britain's Daily Star Sunday newspaper that he has been heavily drinking since February 2014 after he overcame an addiction to sleeping pills. He believes his arrest was a wake-up call and he will head to The Priory rehab facility in London to get help, reports contactmusic.com.
"I know I've let people down. Being arrested and ending up in a cell was the biggest wake-up call to me. It made me realise there is a problem I can't keep ignoring. I need to do something about it," he said.
"Me going to rehab isn't a cop-out. I still take full responsibility for the way I've behaved. There is nobody to blame but myself and I'm deeply ashamed of what has happened. I am doing this because I have finally admitted I need help. I want to stop hurting the people around me," he added.
The singer was released on bail on April 11 night and is due to appear at Ealing Magistrates' Court here on May 2.